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Q1. (a) Copper is a metal. Explain how it conducts electricity.
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(b) Graphite is a non-metal.
Use the information to explain why graphite conducts electricity.
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(Total 5 marks)
Q2. (a) The diagrams represent the atomic structures of two gases, hydrogen and helium.
Hydrogen gas is made up of diatomic molecules (molecules with two atoms). Helium gas exists as single atoms.
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(i) How is a molecule of hydrogen formed from two hydrogen atoms? (You may use a diagram as part of your answer)
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(ii) Why does helium exist only as single atoms?
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(b) Hydrogen combines with carbon to form methane. Each molecule contains four hydrogen atoms strongly bonded to a carbon atom.
Explain why methane has a low boiling point.
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(Total 6 marks)
Q3. (a) Write down the symbols for
lithium ................................................................................
fluorine ............................................................................... (2)
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(b) The electronic structure of a lithium atom can be shown like this:
In a similar way, complete this diagram to show the electronic structure of a fluorine atom.
(1)
(c) A lithium atom can lose one electron to form a lithium ion which can be written (2)+
A fluorine atom can gain one electron to form a fluoride ion.
Choose from the list the correct way to write the fluoride ion.
(2,6)+ (2,7)+ (2,7)- (2,8)+ (2,8)–
Answer .......................................... (2)
(Total 5 marks)
Q4. The diagrams show the giant structures of sodium chloride and diamond.
sodium chloride (melting point 801°C) diamond (melting point 4800°C)
(a) The equation shows how sodium choride could be formed.
Balance the equation.
Na + Cl2
→ Na Cl
(1)
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(b) By reference to the detailed structure of sodium chloride explain fully why:
(i) sodium chloride has a quite high melting point,
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(ii) solid sodium chloride melts when it is heated strongly,
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(iii) molten sodium chloride will conduct electricity.
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(c) By reference to the detailed structure of diamond, explain why the melting point of diamond, is higher than that of sodium chloride.
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(Total 7 marks)
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Q5. (a) The diagrams below show the electronic structure of a magnesium atom and a magnesium ion.
What is the charge on the magnesium ion? ............................................................... (2)
(b) Calcium bromide has the formula CaBr2.
What does this tell you about the ions in this compound?
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(Total 4 marks)
Q6. The diagram shows one molecule of the compound ammonia.
Write down everything that the diagram tells you about each molecule of ammonia.
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##
Atoms of calcium, phosphorus and fluorine are represented below, each with its mass number and proton number.
(a) Use this information to complete the table.
(3)
CALCIUM PHOSPHOROUS FLUORINE
Number of protons in the nucleus 20 9
Number of neutrons in the nucleus 20 16
Number of electrons 15 9
(b) Calcium and fluorine atoms can combine to form the compound calcium fluoride, CaF2.
The fluoride ion is represented by F–.
(i) Explain how the fluorine atom forms a fluoride ion.
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(ii) How is the calcium ion represented?
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(c) Phosphorus and fluorine form a covalent compound, phosphorus trifluoride.
Complete the sentences below which are about this compound.
Phosphorus trifluoride is made up of phosphorus and fluorine ................................
These are joined together by sharing pairs of ............................................... to form
phosphorus trifluoride ........................................................ . (3)
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(d) (i) Sodium chloride, an ionic compound, has a high melting point whereas paraffin wax, a molecular compound, melts easily.
Explain why.
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(ii) Molten ionic compounds conduct electricity but molecular compounds are non-conductors, even when liquid.
Explain why.
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(Total 14 marks)
Q8. The diagram shows the elements in Group 4 of the periodic table.
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Carbon is a non-metal and silicon is usually considered to be a non-metal.
Tin and lead have all the usual properties of metals.
Germanium has these properties:
• grey-white shiny solid
• melting point 937°C
• semi-conductor
• reacts with chlorine to form the chloride (GeCl4) which is a liquid
molecular compound
• germanium oxide reacts with acids to form a salt solution and water. It also reacts with alkalis.
(a) With reference to their structure, explain why tin and lead are good conductors of electricity.
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(b) Would you classify germanium as a metal or as a non-metal? Give your reasons.
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(Total 6 marks)
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Q9. (a) Balance these chemical equations.
(i) H2 + O
2 → H
2O
(1)
(ii) Al + O2 → Al
2O
3
(1)
(b) Briefly explain why an unbalanced chemical equation cannot fully describe a reaction.
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(c) Explain, as fully as you can, why a water molecule contains two hydrogen atoms but a hydrogen chloride molecule contains only one.
(You may use a diagram in your answer if you wish).
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(Total 7 marks)
Q10. (a) The formula for ammonia is NH3. What does the formula tell you about each molecule
of ammonia?
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(b) Ammonia is used to make nitric acid (HNO3). Calculate the formula mass (Mr) for nitric
acid. (Show your working).
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(Total 6 marks)
Q11. The questions which follow refer to the element hydrogen.
(a) Draw a diagram to show the bonding in one molecule of hydrogen.
(2)
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(b) The table gives information about two compounds which contain hydrogen.
Use the information in the table to explain why it is difficult to classify hydrogen as a metal or a non metal.
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(Total 6 marks)
Q12. Sodium carbonate reacts with acids.
(i) Complete the word equation.
sodium carbonate + hydrochloric acid → sodium chloride + ...................... + water (1)
(ii) Name the salt produced if sodium carbonate reacts with dilute nitric acid.
........................................................................................................................... (1)
(Total 2 marks)
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Q13. (a) The chart shows the reactions of the metal calcium with water, oxygen and dilute hydrochloric acid.
Name (i) solution A .................................................................................................
(ii) solid B .....................................................................................................
(iii) gas C ........................................................................................................ (3)
(b) The diagrams below show the electronic structure of an atom of calcium and an atom of oxygen.
Describe fully what happens to its electrons when:
(i) a calcium atom forms a calcium ion. State the charge on the calcium ion formed.
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(ii) an oxygen atom forms an oxygen ion. State the charge on the oxygen ion formed.
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(c) Calcium oxide is an ionic compound. Why do ionic compounds have high melting points?
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(Total 11 marks)
Q14. (a) By reference to their structure, explain how the particles in a piece of metal are held together and how the shape of the metal can be changed without it breaking.
(You may use a diagram in your answer.)
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(5)
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(b) Explain why metals are good conductors of electricity and suggest why this conductivity increases across the periodic table from sodium to magnesium to aluminium.
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(Total 9 marks)
Q15. Chlorine will combine with the non-metal element, carbon, to form this molecular compound.
(a) What is the type of bond in this molecule?
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(b) Explain how these bonds are formed. (You may use a diagram).
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(2)
(Total 3 marks)
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Q16. Magnesium oxide is a compound, made up of magnesium ions and oxide ions.
(a) What is the charge on each magnesium ion? ............................................................. (1)
(b) Explain how the magnesium ions get this charge.
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(Total 3 marks)
Q17. Part of a reactivity series is:
(a) Carbon is used in blast furnaces to obtain iron and zinc from their oxides, but electrolysis has to be used to obtain aluminium from its oxide.
Draw an arrow on the reactivity series above to show where carbon fits into the series. (1)
(b) Predict the method of extraction used to obtain calcium from its ore and explain your answer.
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(c) The formula for zinc oxide is ZnO. Write a balanced equation for the extraction of zinc in the blast furnace.
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(Total 5 marks)
Q18. (a) The equation for the reaction that takes place when ammonium chloride is heated is:
NH4Cl(s) NH
3(g) + HCl (g)
ammonium chloride ammonia hydrogen chloride
The diagram shows how a teacher demonstrated this reaction. The demonstration was carried out in a fume cupboard.
(i) Apart from the gases normally in the atmosphere, which two gases would be at X?
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(ii) Name the white solid that has formed at Y.
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(iii) Why was the demonstration carried out in a fume cupboard?
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(iv) Complete the four spaces in the passage.
The chemical formula of ammonia is NH3. This shows that there is one atom of
.......................................... and three atoms of .................................. in each
......................................... of ammonia. These atoms are joined by bonds that
are formed by sharing pairs of electrons. This type of bond is called
a ............................... bond. (4)
(b) Electrons, neutrons and protons are sub-atomic particles.
(i) Complete the three spaces in the table.
(2)
Name of sub-atomic particle
Relative mass Relative charge
............................... 1 +1
............................... 1 0
...............................
–1
(ii) Which two sub-atomic particles are in the nucleus of an atom?
........................................................... and ............................................... (1)
(Total 10 marks)
Q19. (a) The diagram shows part of the ionic lattice of a sodium chloride crystal.
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(i) Complete the spaces in the table to give information about both of the ions in this lattice.
(2)
Name of ion Charge
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(ii) When it is solid, sodium chloride will not conduct electricity. However, molten sodium chloride will conduct electricity. Explain this difference.
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(iii) Complete the sentence.
Sodium chloride conducts electricity when it is molten and when it is
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(b) The symbol for a calcium atom can be shown like this:
(i) What is the mass number of this atom?
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(ii) What information is given by the mass number?
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(c) Calcium burns in oxygen with a brick-red flame. The product is a white solid. It is calcium oxide and its formula is CaO.
(i) Balance the chemical equation for the reaction.
Ca(s) + O2(g) → CaO(s)
(1)
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(ii) Describe, in terms of electrons, what happens to a calcium atom when it becomes a calcium ion.
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(Total 10 marks)
Q20. Part of the Periodic Table showing the symbols for the first twenty elements is given below.
(a) Draw diagrams showing the arrangement of electrons (electronic structures) in:
(i) an aluminium atom;
(ii) a chlorine atom.
(2)
(b) (i) Use electronic structures to help you show why the formula of sodium oxide is Na2O.
(3)
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(ii) State why the formation of sodium ions is classified as an oxidation.
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(Total 6 marks)
Q21. Ammonium nitrate and ammonium sulphate are used as fertilisers.
(i) Which acid reacts with ammonia to form ammonium nitrate?
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(ii) Which acid reacts with ammonia to form ammonium sulphate?
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(iii) The reactions in (i) and (ii) are both exothermic. How can you tell that a reaction is exothermic?
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(iv) The reactions in (i) and (ii) are both examples of acid + base reactions. What is the name of the chemical change which takes place in every acid + base reaction?
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(Total 4 marks)
Q22. The drawing shows a container of a compound called magnesium chloride.
(i) How many elements are joined together to form magnesium chloride?
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(ii) Magnesium chloride is an ionic compound. What are the names of its ions?
................................................. ions and ................................................. ions (1)
(iii) How many negative ions are there in the formula for magnesium chloride?
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(iv) Complete the sentence.
Ions are atoms, or groups of atoms, which have lost or gained
......................................... . (1)
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(v) Suggest three properties which magnesium chloride has because it is an ionic compound.
Property 1 ...................................................................................................................
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Property 2 ..................................................................................................................
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Property 3 ..................................................................................................................
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(Total 7 marks)
Q23. (a) Atoms are made of sub-atomic particles. Complete the six spaces in the table.
(3)
Name of sub-atomic particle
Relative mass Relative charge
.................................
......................
Neutron ..................... .......................
................................. 1 .......................
(b) Complete the spaces in the sentences.
(i) The atomic number of an atom is the number of ..................................... in its
nucleus and is equal to the number of ..................................................... if the
atom is not charged. (1)
(ii) The mass number of an atom is the total number of ................................. and
...................................... in its nucleus. (1)
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(c) The table gives information about the atoms of three elements.
Two of these elements can react together to form a chemical compound.
Name of element
Chemical symbol
Number of electrons in:
1st
shell 2nd
shell 3rd
shell
Fluorine F 2 7 0
Neon Ne 2 8 0
Sodium Na 2 8 1
(i) What is the name and the formula of this compound?
Name ................................................... Formula .......................................... (2)
(ii) What type of bonding holds this compound together?
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(iii) Explain, in terms of electron transfer, how the bonding occurs in this compound.
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(Total 10 marks)
##
In this question you will need to use the following information:
Relative atomic masses: H 1; O 16; Mg 24.
The volume of one mole of any gas is 24 dm3 at room temperature and atmospheric pressure.
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The diagram shows a chemical reaction taking place in a conical flask.
The balanced equation for this reaction is:
Mg(s) + 2HCl(aq) → MgCl2(aq) + H
2(g)
(a) Write a balanced ionic equation for this reaction.
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(b) Calculate the mass of magnesium required to produce 0.50 g of hydrogen. Show clearly how you work out your final answer and give the unit.
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Mass = ............................... (2)
(c) (i) Draw a diagram to show how the electrons are arranged in a hydrogen molecule.
(1)
(ii) What is the name of the type of chemical bond between the hydrogen atoms in a hydrogen molecule?
........................................................................................................................... (1)
Page 24 of 57
(d) The chemical formula for hydrogen peroxide is H2O
2.
Calculate, to the nearest whole number, the percentage, by mass, of hydrogen in hydrogen peroxide. Show clearly how you work out your answer.
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Percentage = ................................. % (2)
(Total 8 marks)
Q25. Electrons, neutrons and protons are sub-atomic particles.
(a) Complete the six spaces in the following table.
(3)
Name of sub-atomic particle
Relative mass Relative charge
....................................... 1 ........................................
....................................... ........................................ 0
.......................................
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(b) An aluminium atom has 13 electrons. How are these arranged in shells around the nucleus?
.................................................................................................................................... (1)
(c) Chromium atoms have 24 protons and 28 neutrons.
(i) How many electrons does each neutral chromium atom have?
........................................................................................................................... (1)
(ii) What is the mass number of chromium?
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(d) What change occurs to an atom which undergoes the process of reduction in a chemical reaction?
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Page 25 of 57
(e) The diagram shows part of the ionic lattice of a sodium chloride crystal.
Explain why the ions in this lattice stay in place.
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(Total 10 marks)
Q26. (a) Every chemical element has a chemical symbol. Choose the correct chemical symbols from the box and complete the three spaces in the table.
(3)
C Co Cu Fe I Ir Zn Zr
Name of element Chemical symbol
Copper ....................................
Iron ....................................
Zinc ....................................
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(b) Give one use for each of the following metals. You should give a different use for each metal.
Copper ......................................................................................................................
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Iron ...........................................................................................................................
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Zinc ...........................................................................................................................
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(c) Give four physical properties which metals usually have.
1. ................................................................................................................................
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2. ................................................................................................................................
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3. ................................................................................................................................
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4. ................................................................................................................................
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(d) Metals usually form ionic compounds. Give one property of an ionic compound.
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(e) The diagrams show two different atoms, atom A and atom B.
Atom A Atom B
(i) Complete the following sentence.
For these two atoms to become ions one ............................................ would
be transferred from atom ........... to atom ........... . (1)
(ii) Atom A and atom B are from different elements. How can you tell this from their nuclei?
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(Total 13 marks)
Q27. (i) Complete the drawing to show the electron structure of a hydrogen fluoride molecule. Draw electrons as dots or crosses.
(1)
Page 28 of 57
(ii) Explain why hydrogen fluoride is a gas at room temperature.
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(Total 3 marks)
Q28. (a) A piece of lithium is placed on the surface of some water in a beaker. Hydrogen is given off. Lithium hydroxide is also formed.
Write a word equation for this reaction.
..................................................................................................................................... (2)
(b) The diagram shows the structure of a molecule of methane.
Write down everything that this diagram tells you about a methane molecule.
To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words.
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(Total 6 marks)
Page 29 of 57
Q29. The diagram shows the structure of diamond.
(a) To gain full marks for this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words.
Explain, as fully as you can, why diamond has a high melting point.
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(b) The diagram below shows the outer electron shells of five carbon atoms in the giant lattice of diamond.
Carbon atom C forms bonds with each of the carbon atoms W, X, Y and Z.
Draw the positions of all the electrons in the outer shells of each of carbon atoms C, W, X, Y and Z.
(3)
(Total 6 marks)
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Q30. The diagram shows the structure of diamond.
(a) To gain full marks for this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words.
Explain, as fully as you can, why diamond has a high melting point.
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(b) The diagram below shows the outer electron shells of five carbon atoms in the giant lattice of diamond.
Carbon atom C forms bonds with each of the carbon atoms W, X, Y and Z.
Draw the positions of all the electrons in the outer shells of each of carbon atoms C, W, X, Y and Z.
(3)
(Total 6 marks)
Page 33 of 57
M1. (a) idea that
• copper has free electrons / electrons that move throughout the structure
gains 1 mark
but
• in copper, electrons from the highest (occupied) energy level /outer shell, are free / can move throughout the structure
gains 2 marks 2
(b) idea that
• in graphite, only three bonds are formed by each carbon atom for 1 mark
• one outer electron (per atom), free to move for 1 mark
• an electric current is a flow of (free) electrons* for 1 mark
(* this mark to be given in either (a) or (b) but not in both) 3
[5]
M2. (a) (i) idea that
• two hydrogen atoms share one pair of electrons
• linked by a covalent bond
• each then has two outer electrons / a full outer shell / two
• electrons in the highest (occupied) energy level
(2 marks may be awarded for a correct electron diagram i.e. with electrons on boundary of or within marked area).
any two for 1 mark each 2
Page 34 of 57
(ii) idea that
• helium atoms do not give / take / share electrons / react
• because the (outer) shell / orbit is full
or
• highest (occupied) energy level is full
(but not just “contains two electrons”) for 1 mark each
2
(b) idea that
• the (attractive) forces between molecules are weak
(not bonds between atoms)
• so little energy is required / it is easy for molecules to escape from the liquid* / escape from other molecules*
(allow evaporate / change into a gas) for 1 mark each
2 [6]
M3. (a) lithium = Li
(ignore mass / atomic numbers) fluorine = F (do not allow if case is incorrect) for 1 mark each
2
(b) (allow ● or o for electrons) (allow any positions for the seven electrons added provided they are on the outer ring)
for 1 mark 1
(c) (2,8)+ or (2,7)–
(brackets not required) gains 1 mark
but (2,8)–
gains 2 marks 2
[5]
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M4. (a) 2 Na + Cl2 → 2 NaCl
allow 2 Na+ Cl– for 1 mark
(allow Na + ½Cl2 → Na Cl) 1
(b) (i) idea that
• it has strong (attractive) forces/bonds between ions / charged particles for 1 mark
(not ‘..it has a rigid structure’- this defines a solid or ‘...particles close together’ – they are in a liquid)
1
(ii) ideas that
• there is increased vibration of ions / particles on heating
• ions have sufficient energy to overcome attractive forces / to break out of the
• rigid structure / to move about
(must be in terms of increased energy of particles lions) each for 1 mark
2
(iii) • ions can go to electrodes / ions are free to move for 1 mark [do not credit ‘ions carry charges’]
1
(c) ideas that
• it has stronger attractive forces between atoms/particles (not ‘ions’)
• each carbon atom forms covalent bonds with neighbouring atoms each for 1 mark
2 [7]
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M5. (a) positive / + / 2
gains 1 mark
but 2+ / ++ / +2
gains 2 marks 2
(b) Ideas that: 2
Ca2+
Br- [Do not disqualify for "bromine" ions] Ions / They are in the ratio 1:2
any two for 1 mark each 2
[4]
M6. idea that
• contains nitrogen atoms
• contains hydrogen atoms
• atoms are chemically bonded NOT linked/joined
• ratio of one nitrogen to three hydrogen (atoms) formula of ammonia is NH3
for 1 mark each [4]
M7. (a)
for 1 mark each
3
Calcium Phosphorus Fluorine
No of protons 15
No of neutrons 10
No of electrons 20
(b) (i) gain of electron(s)
from (atoms) (of) calcium for 1 mark
2
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(ii) Ca+
gains 1 mark
but superscript only Ca2+ / Ca ++
gains 2 marks 2
(c) atoms electrons molecule(s) not compound
each for 1 mark 3
(d) (i) ideas that
• ionic – strong forces between ions
• molecular – weak forces between molecules each for 1 mark
2
(ii) ideas that
• ionic – ions/charged particles are free to move
• molecular -molecules do not carry a charge each for 1 mark
2 [14]
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(a) idea that some of the outer electrons of the atoms are free to move can move anywhere across the (giant) structure the flow of electricity is a stream of electrons
each for 1 mark
or electrons carry a (negative electrical) charge 3
Page 38 of 57
(b) metal element [shiny] appearance
[high] melting point forms an oxide that reacts with acids to make a salt
1 of these for 1 mark
non metal element forms an oxide that reacts with alkalis
with chlorine forms a molecular chloride 1 of these for 1 mark
semi-conductor suggests in between this, or any other for 1further mark
[NB Maximum of 2 for arguing metal/non-metal only] Under each head 1 wrong reason → maximum of 1 available 2 wrong reasons → no mark available]
3 [6]
M9. (a) (i) 2 H2 + O
2 → 2 H
2O (allow H
2 + ½O
2 → H
2O)
both circled for 1 mark 1
(ii) 4 A1 + 3 O2 → 2 A1
2O
3
all circled for 1 mark 1
(b) idea that: must end up with the same number of atoms otherwise matter is shown to be lost/gained doesn’t show correct amount of each element/compared
each for 1 mark 2
(c) idea that: oxygen has 2 electrons short in outer shell ) in words or chlorine has 1 electron short in outer shell ) indicated on diagram (shared pair/covalent bond with) hydrogen atom supplies one further electron* *(but do not allow hydrogen gives away electron or ionic bond)
for 1 mark each 3
[7]
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M10. (a) reference to hydrogen (atoms) ) nitrogen (atoms) ) but not molecules
each for 1 mark
ratio of 1N to 3H atoms
for 1 further mark
or 1 nitrogen atom and 3 hydrogen atoms (ignore any incorrect statements about nature of bonding)
3
(b) evidence of H = 1 N = 14 O = 16
gains 1 mark
but H = 1 N = 14 O = 16 × 3 or 48
gains 2 marks
but 63
gains 3 marks 3
[6]
M11. (a) correct representation of 1 atom of hydrogen e.g.
gains 1 mark
but correct representation of 1 molecule of hydrogen e.g. or H-H
gains 2 marks
2
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(b) idea that: hydrogen/metals form positive ions/lose electrons
gains 1 mark
but hydrogen and the metals form positive ions/lose electrons
gains 2 marks
hydrogen/non-metals form covalent bonds/share electrons gains 1 mark
but hydrogen and the non-metals form covalent bonds/share electrons
gains 2 marks 4
[6]
M12. (i) carbon dioxide (allow CO2)
for 1 mark 1
(ii) sodium nitrate (accept correct formula) for 1 mark
1 [2]
M13. (a) (i) A calcium hydroxide/limewater/Ca(OH)2 not CaOH
(ii) B calcium oxide/Quicklime/CaO
(iii) C hydrogen/H2 (accept correct formulae)/ not H
2/H
each for 1 mark 3
(b) (i) idea that electrons are lost (by the calcium atom)
gains1 mark
but two electrons are lost (by the calcium atom)/lose outer electrons to get full shell
gains 2 marks
calcium ions are 2+ for 1 mark
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(ii) electrons are gained (by the oxygen atom) gains 1 mark
but two electrons are gained (by the oxygen atom)/gain electrons to get full outer shell
gains 2 marks
oxygen ions are 2– for 1 mark
6
(b) (i)(ii) needs: electron loss/gain number (2) charge (+/–)
(c) idea that they are held together by many/strong forces/bonds a lot of energy/high temperature is required to break these forces/bonds
each for 1 mark 2
[11]
##
(a) Idea that the electrons do not belong to specific atoms/delocalised electrons [credit if done on appropriate diagram] metal atoms form positive ions the attraction which exists between particles with opposite charges, holds the metal together no specific bonds exist between adjacent atoms/ions atoms/ions can slide over each other so allowing metals to bend
each for 1 mark 5
(b) some electrons in the structure are delocalised/free to move for 1 mark
these free electrons carry the electric current for 1 mark
from left to right across the period, atoms of elements have more free electrons
gains 1 mark
but from left to right across the period, atoms of elements have more free electrons because they have more electrons in the outer shells
gains 2 marks 4
[9]
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##
(a) covalent bonds for 1 mark
1
(b) any reference to shared electrons gains 1 mark
but idea that bond is shared pair of electrons
gains 2 marks 2
[3]
##
(a) positive for 1 mark
1
(b) any reference to loss of electrons for 1 mark
reference to charge being +2 (in (a)) or to loss of 2 electrons (in (b))
for 1 mark 2
[3]
M17. (a) This part was not marked 1
(b) electrolysis 1
because calcium is more reactive (than aluminium or carbon)
accept it is more reactive or very reactive
1
OR
in a blast furnace 1
because calcium is less reactive (than carbon or lower) 1
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(c) any equation from 1 mark for correct formulae 1 mark for balancing
2ZnO + C → 2Zn + CO2
ZnO + CO → Zn + CO2
ZnO + C → Zn + CO 1
[5]
M18. (a) (i) ammonia and hydrogen chloride
both required either order accept formulae if correct in every detail
1
(ii) ammonium chloride / NH4Cl
do not credit ammonia chloride 1
(iii) the fumes / gases / are poisonous / toxic or ammonia and hydrogen chloride are poisonous / toxic / lethal accept just ammonia is poisonous / toxic accept just hydrogen chloride is poisonous / toxic accept vapour is poisonous / toxic do not credit just fumes are dangerous or harmful
1
(iv) nitrogen do not credit N/N
2
1
hydrogen do not credit H/H
2
1
molecule do not credit compound or mole
1
covalent accept single / molecular
1
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(b) (i) proton
neutron
electron either all three correct or one or two correct however do not credit a response which is repeated
2
(ii) protons and neutrons both required in either order
1 [10]
M19. (a) (i) sodium........ positive or +
both required 1
chloride... negative or –
both required do not credit chlorine
1
(ii) ions not free (to move) in solid crystal / lattice
ions are free to move when sodium chloride is molten 1
or ions are mobile
do not credit when ions are molten allow 'particles' for ions (1) mark do not credit electrons etc
1
(iii) dissolved in water or in aqueous solution accept in solution accept in water or when a gas/ vapour or solid it will not
1
(b) (i) 40 1
(ii) (total) number of protons and neutrons (in the nucleus) 1
(c) (i) 2Ca + O2 -+ 2CaO
accept any 2n : n : 2n ratio do not credit if any other change has been made
1
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(ii) any two from
electron(s) is / are lost
from the outer shell / orbit / ring or from the shell furthest the nucleus or from the 4th shell
two / both (electrons are lost) accept two electrons are lost for (2)marks accept both electrons are lost from the atom for (1) mark
2 [10]
M20. (a) (i) rings of 2, 8 and 3 electrons
credit 2, 8, 3 pay particular attention to the outer shell in diagrams 1
(ii) rings of 2, 8 and 7 electrons credit 2, 8, 7 pay particular attention to the outer shell in diagrams
1
(b) (i) labels not required on atoms charges need to be shown on ions reference to outer shell is required otherwise a maximum of two marks
structure of atoms/ions marks
(ring of 2, 8, 1 for sodium) or the outer shell of sodium only contains 1 electron
credit 2, 8, 1 or an ion 2, 8 or two circles and 1 electron in outer shell
1
(ring of 2, 6 for oxygen) or outer shell only contains 6 electrons
credit 2, 6 or an ion 2, 8 or two circles 1
transfer of electrons mark
two sodiums needed to supply two outer electrons to oxygen to complete the (one oxygen's) outer shell
award maximum of two marks if a covalent structure is given credit two rings of electrons for sodium showing outer electrons transferring to outer shell of one oxygen for three marks do not accept diagrams showing overlapping rings for third mark
1
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(ii) loses an electron credit atoms lose electrons or oxygen takes the electron ignore oil rig
1 [6]
M21. NOTE
In this question and throughout the Paper, if the name of a chemical is asked for, then the formula is acceptable only if it is correct in every detail. If the name is correct and the candidate has tried to be ‘helpful’ by giving, in addition, an incorrect version of the formula, then this is acceptable provided it does not lead to ambiguity.
(i) nitric (acid) accept HN0
3
1
(ii) sulphuric (acid) accept H
2SO
4
1
(iii) heat given out or temperature rise or energy given out or steam do not credit just ‘use a thermometer’ do not credit just 'change in temperature'
1
(iv) neutralisation accept neutralise accept neutral accept formation of salt or water do not credit exothermic
1 [4]
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M22. (i) two
or 2 1
(ii) magnesium and chloride
either order not positive / negative do not credit’chlorine’
accept Mg++ and Cl-
do not credit just Mg and Cl–
accept cation(s) and anion(s) 1
(iii) 2 1
(iv) electrons accept charges
1
(v) any three from
• (is a) giant structure/lattice structure
• crystalline / hard accept just 'crystals(s)’
• high melting point / solid
• high boiling point
• conductor (of electricity) when dissolved in water
or conductor (of electricity) when ions are free to move
• conductor (of electricity) when molten
• soluble in water 3
[7]
M23. (a)
both correct in each row
electron ...– (1) allow negative
1
1 .......... 0 allow neutral or none
1
proton .....+ (1) allow positive
1
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(b) (i) protons...electrons both correct in correct order
1
(ii) protons....neutrons both correct in either order
1
(c) (i) sodium fluoride do not credit sodium fluorine
1
NaF must be correct in every detail do not credit NAF and the like
1
(ii) ionic accept ion (bonding) do not credit ironic or iron (bonding)
1
(iii) electron transferred from sodium to fluorine accept electron transferred from metal to non-metal
either positive sodium ion and negative fluoride ion
or correctly identified by the symbols Na+ and F- accept ‘positive sodium ion and negative fluorine ion’
1
or attracted because have opposite charge(s)
or (atoms/ions) form an (ionic) lattice or (atoms/ions) form a crystal e.g.
or both marks may be gained by a suitable dot and cross diagram 1
[10]
M24. (a) Mg + 2H+ → Mg2+ + H2
* reactants correct in every detail * products correct in every detail
if the spectator ions are sown then (1) mark should be credited but only if they are shown correctly on both sides e.g.
Mg + 2H+ + 2CI- → Mg2+ + 2CI- + H2
2
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(b) 24 (parts) of magnesium → 2 (parts) 1
of hydrogen or equally clear working (so) 6 grams/g (are needed) 1
unit required
(c) (i) two (and no more) atoms shown to be sharing their single electrons examples
do not credit if anything which contradicts the impression that these are hydrogen atoms
1
(ii) (single) covalent (bond) 1
(d) (×100) = 6 (just 6 is worth (1) mark) 1
× 100 = 6 or similar is (0)
do not credit 5.8823529 and the like
1 [8]
M25. (a) proton + (1)
both required
neutron 1 both required
electron – (1) both required
3
(b) 2.8.3 accept words or diagram to this effect
1
(c) (i) 24 1
(ii) 52 1
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(d) any one of
• gains one or more electrons accept gains an electron
• becomes an anion do not credit becomes an ion
• becomes a negative ion 1
(e) sodium ions have a (single) positive charge and chloride ions have a (single) negative charge
do not credit ‘chlorine ions’ but allow this error to be carried forward
1
ions with opposite charge are attracted (to each other)
or the positive ions and the negative ions are attracted (to each other) or the sodium ions and the chloride ions are attracted (to each other)
1
(positive and negative) ions are arranged alternatively (in each direction or dimension)
or ions with the same charge are repelled (by each other) no mark for just ionic bonds
1 [10]
M26. (a) Cu 1
Fe 1
Zn 1
(b) one significant use for each metal
do not credit vague answers such as ‘in experiments’ and the like do not credit the same use more than once
copper examples:
do not credit diet supplement 1
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• coins or coinage (metal) or make alloys or bronze or brass
• conducting electricity or (electrical) wiring or motors or cables
• (domestic) (water) pipes
• heat exchangers
• roofing
• steam pipes
• stills or cooking utensils
accept any specified still e.g. whisky still
• bracelets or rings
iron or steel answers examples:
do not credit diet supplement
* access-hole covers (sometimes known as ‘manhole’ covers) * catalyst (in the production of ammonia) * manufacture of steel(s) or in the basic oxygen process * named vehicle or transport or machinery or railings
any other uses for iron and steel can be credited provided that the use is clear so, for example, ‘bridges’ and ‘railway lines’ would be creditworthy but do not credit ‘buildings’ and ‘transport’ which are too vague
1
zinc examples:
do not credit diet supplement
* brass manufacture * die castings * rust prevention * to galvanise (iron or steel) or (as a) protective coating * battery casing
1
(c) any four general properties of
do not credit hard or strong or tough or magnetic
• are not brittle accept can be bent (into shape) or flexible
• can be hammered (into shape) accept are malleable
• can be stretched (into shape) accept are ductile
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• (good) conductors of heat accept just ‘(good) conductor’ once only
• (good) conductors of electricity
• high boiling points
• high density or heavy or dense
• high melting points
• ringing sound when struck accept sonorous
• solids (at room temperature) accept shiny (when polished) or silvery
4
(d) any one of
do not credit electron references
* (good) conductor (of electricity) when molten or liquid accept dissolves in water or crystalline
* (good) conductor (of electricity) when in aqueous solution accept (good) conductor (of electricity) when dissolved in water
* high melting point or high boiling point
do not credit just ‘solid’ 1
(e) (i) electron from A to B both parts required
1
(ii) different numbers of protons accept different atomic numbers do not credit references to neutrons
1 [13]
M27. (i) 1
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(ii) weak forces accept weak bonds
1
between molecules / intermolecular reject intramolecular
1 [3]
M28. (a) LHS lithium + water
accept Li and H2O
accept hydrogen oxide for water 1
RHS hydrogen + lithium hydroxide accept H
2 and LiOH
ignore attempts at balancing ignore charges
1
(b) Quality of written communication
One mark for the correct use of any three of the terms atom, covalent, bond(ing), saturated, hydrocarbon or alkane
1
any three from:
one / the carbon (atom) reject molecules once
four hydrogen (atoms) shape / properties neutral
CH4
hydrocarbon
saturated / single bond
covalent bond / shared electrons
alkane reject ionic bond
3 [6]
Page 54 of 57
M29. (a) Quality of written communication: All scientific words used correctly (covalent, bonds, atoms)
1
any two from
• large numbers of covalent bonds allow giant lattice / structure
• between atoms do not accept between molecules
• (covalent) bonds strong accept need much energy to break
2
(b)
each carbon has 4 electrons 1
one shared pair 1
four shared pairs 1
[6]
Page 55 of 57
M30. (a) Quality of written communication: All scientific words used correctly (covalent, bonds, atoms)
1
any two from
• large numbers of covalent bonds allow giant lattice / structure
• between atoms do not accept between molecules
• (covalent) bonds strong accept need much energy to break
2
(b)
each carbon has 4 electrons 1
one shared pair 1
four shared pairs 1
[6]
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